Sewing-machine.



R. K. HOHMANN.

SEWING MACHINE.

APPLICATION FILED IuLY 6, 1914. Ll.

Patented Deo. 21, 1915.

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R. K. HOHMANN.

SEWING MACHINE.

APPLICATION FILED IuLY e, I9I4.

Patented Dec. 21, 1915.

Noun/IPH co.. WASHINGTON. D. c4

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BICI-IARD K. HOHIVIANN, 0F BELVIDERE, ILLINOIS, ASSIGNR T0 NATIONAL SEWING MACHINE COMPANY, OF BELVIDERE, ILLINOIS, .A CORPORATION OF ILLINOIS.

SEWING-MACHINE.

Speciicaton of Letters Patent.

Patented Dec. 21, 119115.

Application filed July 6, 1914. Serial No. 849,083.

provide an improved structure of this character which will be simple, durable and reliable in construction and effective and eilicient in operation.

Other objects of my invention will appear hereinafter.

Referring to the accompanying drawings: Figure 1 is a view of the end of the sewing machine head with the end plate removed, the bed plate shown in section, and the takeup mechanism and shuttle shown in one of their relative positions. Fig. 2 is a view similar to Fig. 1 showing the take-up and shuttle mechanisms in a different position. Figs. 3, 4, 5, 6, 7 and 8 are diagrammatic views showing various portions of take-up mechanism atdiiferent points in the cycle of operation wherein a stitch is made.

It will be obvious to one skilled in the art, after having obtained an understanding of my invention from the disclosures herein made, that my invention is capable of being variously modified and rearranged without departing from the scope and spirit of the invention, and I wish it so understood.

Referring more particularly to the drawings, I have indicated the bed plate of a sewing machine at 1, the head at 2 and the driving shaft, which is journaled in the head 2, at 3. I have not shown the connection between the head 2 and bed plate l, or the driving means for'the shaft 3 since these parts are of the ordinary construction and well known. Under' the plate 1 is an oscillatory shuttle carrier 11, also of the usual construction and the details ofwhich are not shown. Riding in the shuttle carrier 11, and propelled by the turned .portion 12 thereof, is a shuttle C of the usual construction and having flattened sides 19 and 2O adapted to slide against a guide, not shown,

to prevent rotation. @t the Shuttle- .The shattle is provided with the usual sharp point adapted to enter the loop made up of portions D1 and D2 of the thread D, which is carried through the plate 1 in the usual manner by a needle 22 set in the end of a needle bar 23.

In the structure shown I have indicated at a feed bar for feeding the cloth. This may, of course, be of any suitable or standard construction and need not be particularly described or shown. The free end of the arm 2 is enlarged in the usual manner to form a box or casing 31 for the take-up mechanism and other parts usual to sewing machines. This casing carries the usual presser foot bar 32 which projects below the casing 31 and carries at its lower end the presser foot 33 which coperates with the feed bar 30 to feed the cloth progressively with respect to the needle. This may be of the ordinary construction and needs no further description. The needle bar 23, prevously referred to, may also be of the ordinary construction having a suitable clamp or fastening device 34 at its lower end for holding the needle 22. This needle bar is journaled at `the upper and lower ends of the casing so that it may be. reciprocated in a vertical line; that is, in a line perpendicular with respect to the line of movement of the shuttle and also per pendicular with respect to the longitudinal axis of the shaft 3. In the construction shown the needle bar is positioned immediately in front of the end of the shaft 3 so that its longitudinal axis passes through theaXis of the shaft 3. This needle bar derives its reciprocating movement from the shaft 3 through the medium of a crank meinber or disk 40 and a connecting link 41. The connecting link is pivotally connected at its lower end 42 to the needle bar. At its upper end 43 it is pivotally connected to the crank member 40 so that the rotation of the crank member will rotate the upper end 43 of the link and thereby reciprocate the needle bar. This crank member is enlarged at one side at 44 to provide a suitable counterweight to balance the rotatingparts.

. The take-up arm is also positioned within the casing 31 and is operated by this mechanism. The eyelet end or free end 45 of the take-up arm 46 extends through a vertical slot 47 in the casing 31. This end @t the; take-.ar alim is, reirfoated n in a substantially vertical plane and operates. as is well known, to draw the loop tight after the shuttle has passed through it and formed the stitch. The thread is brought from a spool, not shown, and passed through the thread check 48, main and auxiliary tension device 49, eyelet 50, thence through the c velet end of the take-up arm as shown in Fig. 1, and thence down through the eye ot the needle. The other or inner end of the takeup arm 46 is pivotally connected at 51 to the connecting link 41, as shown clearly in Figs. 1 and 2. lt will be noted, however, that the connecting link or bar 41 is so formed that the pivotal point 51 of connection of the take-up arm with the link 4l is offset considerably with respect to a. straight' linedrawn between the pivotal points in ends 43 and 42 of said connecting link 41. The take-up arm, as clearly shown in the drawings, extends in a substantially straight line Jfrom its pivotal point of connection 51 with the link 41 to a point 52 'about midway of its ends and at this point '52 it is pivotally connected to one end of a curved link 53, the other end of which is pivotally connected at 54 to a lixed support, `which in this case is the wall of the casing 31. From the pivotal point 52 the take-up arm extends generally at an angle to the portion between the points 51 and 52.

In accordance with my invention the takeup arm operates in a certain timed relation to the movement of the shuttle but it does not move ata uniform speed like the shuttle does on account of the condition of the thread yat various positions ot' the shuttle. When the shuttle enters the loop of thread brought down by the needle the take-up arm will be in a position near the lower end of its stroke and continues to move downwardly until the tapering portion of the shuttle has passed through the loop of the thread, so that the take-up arm will exert no pull on the thread while the shuttle is going through the loop. As soon as the shuttle passes the loop, however, the takeup arm will operate with a rather quick movement upwardly for the purpose of ,drawing or pulling tight the loop which the shuttle made thereby to form the stitch.

In Figs. 3 to 8 I have illustrated in diagram the position of the parts of the takeup mechanism at various points in the cycle of operation thereof. ln these diagrams the irregular dotted line 60 indicates the orbit in which the eyelet end of the take-up arm moves. The dotted line 61 indicates the elliptical orbit in which the pivotal point 51 moves, the dotted line 62 indicates they circular orbit in which the pivotal point of end 43 moves, and the straight line 63 indicates the line of movement of the pivotal point of end 42.

In Fig. 3, end 43 of connecting link 41 and consequently needle 22, are at their lowest positions ot' movement and the shuttle C is at the very beginning of its forward movement, while eyelet 45 has yet a considerable part of its downward movement to be made. Upon beginning the forward movement of the shuttle, and the upward movement of thc needle corresponding thereto, see Fig. 4, the point of the shuttle enters loop D of the thread and prevents the upward movement of the needle from drawing the loop upwardly also. The eyelet 45 continues the downward movement through its positions shown in Figs. 4 and 5 and to a point just before it reaches its position indicated in Fig. 6. This downward movement of the eyelet 45, after leaving its position in Fig. 3, loosens the thread suliiciently so that the entire shuttle may pass through the loop D without placing the thread under tension.

In offsetting the point 51 of the connecting link 41, I provide means whereby the connecting link 41 passes its lower dead center in line 63 just before point 51, in its path G1, passes through a line passing through points 5l and 52 in order to give a very slow motion to the eyelet 45 while the shuttle is passing through the loop D. Fig. 5 diagrammatically illustrates the position of the take-up mechanism parts when the shuttle is about haltl way through the loop of thread, and Fig. 6 illustrates said parts as the shuttle is practically through the loop.

The comparatively large size of the shuttle necessarily causes considerable excess thread to be pulled from the spool in formingT the loop large enough to allow the shuttle to pass through and as soon as the shuttle passes through the loop this excess must be drawn up tight to form a stitch. After leaving the loop the shutle has very little left to finish its stroke in the same direction and in consequence the excess of the loop must be quickly drawn up tight to form the stitch so that the shuttle on its return stroke will not become entangled in the loop.

It will be seen that although the shuttle moves a very little distance in finishing its stroke the take-up mechanism carries the end 45 of the take-up arm upward with a quick motion substantially the entire length of its upward stroke thus quickly drawing the loop of thread tight.

Thus it will be seen that the shuttle mechanism and take-up mechanism are so related and timed with respect to each other that the conditions of the thread at any point in the cycle of operation is properly taken care of by the take-up mechanism with the result that the stitches will be properly formed even though the machine is run at a high speed.

lVhat I claim is:

1 The combination of a shaft, a needle bar, a crank on said Shaft, a connecting link connected to said crank and said needle bar for reciprocating the needle bar, and a takeup arm having one end connected With the connecting link at a point intermediate the ends of and offset from a straight line through the points of connection of the connecting link with the needle bar and crank.

2. The combination of a shaft, a crank on said shaft, a needle bar positioned to reciprocate in a line perpendicular to the longitudinal axis of said shaft, a connecting link between the crank and the needle bar for reciprocating the needle bar, a take-up arm having one end pivotally connected to said connecting link at a point offset With respect to a straight line drawn through the points of connection of said connecting link with the crank and the needle bar and having its other end adapted to oscillate, a fixed support, and a link pivotally connected at one end to said support and at the other end to said take-up arm intermediate the ends of the latter.

In testimony whereof I have signed my name to this specication, in the presence of two subscribing Witnesses, on this 1st day of July, A. D. 1914.

R101-IARD K. HOHMANN.

Witnesses:

JOHN W. ELDREDGE, A. V. FONKEN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

